Pipe thread plug measuring device



INVENTOR- L/ 6L NZEE Byzg fl/YD 2 Sheets-Sheet 1 HTTOIE/VEYS H J GLANZER PIPE THREAD PLUG MEASURING DEVICE Feb. 27, 1951 Filed Aug. 25, 1945 Feb. 27, 1951 J, GLANZER 2,543,012

PIPE THREAD PLUG MEASURING DEVICE Filed Aug. 25, 1945 2 Sheets-Sheet 2 BY fi/YD ZZM W6 Patented Feb. 27, 1951 UNITED S' -TATES PATENT OFFICE (Granted under the act at Marchl3, 1883,.as amended..April.30, 1928;.370 O. G. 757) Claims.

Tha -invention described: herein: mawbe manufactured :andtusedtby orrfor: the; Government for governmental purposeszwithout payment tame of anyrroyaity thereonc: l

'Ifhisrinventionrelateswtoaa device-for :measuring the pitch diameter of a pipe threaduandais particularly. useful: in :checking; thetpitehwdiametersgofii pipeethreadzzplugegauges= at tthevextreme small. endi-iofi thesplugt.

Ans. obfiec-tr of: the: invention). is r to 1 provide a compiemen'taryi gauge: blocks f or; usewinaconnectionuwith a.'.pipe plugegauge whereby the measurement indicated: over. 3 the l pitch diameter of thecplng andtthezeblockiz isstheasameqvat any; distance from the small end of thesplugy atcwhich the: measurement? may; be; taken; whereby the position at which the measurement is takenisinot critical.

Other objects: and: advantages will zbeaevident as the' invention isrfnrtherrdescribedawith ref erence "to: the: drawings. wherein;

Fig: 1 shows the conventional method-of measuring the pitch: diameterrof a. straight U.-. S. standard thread, the diameter of. thetwire-being so calculated as to contact the thread 011-- the pitch diameter-.-

Fig. 2? showsmy; improved; measuring; block for-measuring the pitch diameter 051a; pipes-thread at $13118 end.

Fig; 3: shows a: pipeithread: in .placeeon -my -improved measuring-zblockwwith the measuring wires imposition.-

Fig: i -shows aac'lamp associated with the block for holding the: pipeethreaded test pieceonthe block while-measurement is being takenh Fig. 5:S1 10WS how outsidedi-ameters; of. pipe threads maybe; checked. to determine: whether the=thread is' of proper diameter. atwtheee xtreme small end;

Fig. 6 is axcen tral longitudinal section through the plug-and block.

Lils'ei. reference characters" refer. to: like parts throughout the several views;

Fig. 1; showsaaiconventional-all). S. standard straight. thread aplug-gauge lO-with wires I2. and

52a laid. in place-z-for. the purpose of measuring the pitch. diameter of the plug. The diameters of the wires 52,. and IZCMSJE. so-calculated that they make: contactwith the. pitch lines M whereby" the pitch diameter 551 may readily be determined :bymeasuringoverthe wires I 2. and ma with the anvi s Ha of: a. measuring; instrument.

Since-the included. angle between the. sides of the-thread-itseli is 60? itgissonly. necessary to from the. measurement taken to determine the pitchd-iameter: When no wire-isavailable-of the; exact size which; will 4 make-- contact; at the pitch-diameter,- and an, odd diameter wire is used iinstead, the measurement: over the wires maybefoundby the:iollowing equationz wherein;

M=Measurementi over the wires, P: D.=Pitch diameter, N=Number of threads iper inch', G'=Diameter of 'the wiree The; methodpillustrated in Fig.1 is conventional and well .knowniin :the; art:

Pipe threads. however; are tapered-,3 and: the

pitch diameterxaceordingly:varies throughout the "length: of, thethreadu. The; designation: pitch diameteri when applied toraapipe thread means the pitch diameter taken at the:extreme-small end. Ibis-"obvious; however; that the three wire system: as: known: in the: art': could notwbe employedfor measuring pitchdiametersat-theends of the plugs;

I accordin lyr'prcvidegablock ,asrshown in Fig. 2,: the :side |8Fof-whichziszat :an angle withthe vertical 2 an amount:v equal to the apexangle of theppipeplugtandithe-side 2010f which is at an: angle: with thee. horizontal. an amount" equal to: half the: apex" angle of? the pipe. plug: This will bring the; pitch? line: Mr which is. on the outer; side of E the plugto aatruenvertical :line as seen .in' Fig. 31:. The distance .22' may preferably be: made-.one inch-to, simplify the.determination of the measurement.

With the wires l2; along the edge [8 of the b ock spaced as far apart as convenient and the wire [2a positioned at a height which is anywhere hetweenthesheights of the wires; H! the measurementv may, be taken by. the anvils. l 1 as: shown in.Eig.- 3... By now. subtracting. from themeasurementtaken, thedistance- 22. which is..one1inch.1 anebby, further subtracting. oneand oneha f. diameters. wd.+ wd.. of the wire i2sor. I2a,.the result wherewire whichcontacts the=pitchtdiameter is being used, will he the base bof aright trianglewhoseacute angle (1. adjacent. the basal) ishalf the apex angle of the plu being measured. and whose hypotenuse h is thepitchdiameter taken at the smallendof said. thread, and this is true, regardless of the height oft th'e;wir.es.from thesmall end of the subtract oneand=one-halfgdiameterssofithewires, plug when the measurement was taken, or the 3 V r height of the anvil from the base of the block, assuming of course that the taper of the plug is correct and therefore corresponds to the taper for which the block was made.

In Fig. 4 the block i9 has been provided with a clamp 24 actuated by a screw 26 for holding the plug 28 in place. The device as shown here is being used to check the taper of the plug. To accomplish this the wires l2 on the side !8 'of the fixture are spread as far apart as the length of the plug will permit while the wire 52a the triangle whose base I) is the measurement taken by the anvils less the distance 22, less one and one-half diameters of the Wires l2 and Ma wd mud and the angle a of which is half the apex angle of the thread plug.

Fig. 3 of thedrawings is intended to facilitate an understanding of the procedure for checking the pitch diameter of the plug at the small end. In Fig. 3, the wire diameter makes contact with the sides of the thread on the pitch line of the plug, the wire diameter being designated as wd, whereby the distance from the outside of the wire to the pitch line of the plug is wd. The line b is an extension of the line 22 and therefore is normal to the surface 2i and forms the base of a triangle of which a is the acute angle adjacent the base and h is the hy- The line h being drawn parallel to potenuse. the surface fixes the angle a as half the apex angle of the plug.

7 and knowing the acute angle (1 adjacent the base b to. be one-half the apex angleof the plug the hypotenuse h which is the 'pitch diameter of the plug at the small end may be found by the wall known equation cos. a

outside diameters at the small end. With the plug 28 clamped in themanner shown measurementsmay be taken by the anvils I! at different heights from the base of the block and if these measurements are all alike, .the taper is correct, and if the measurements takerrby the anvils l1 minus the distance 22, shows the desired outside diameter at the small end of the plug, this measurement will be correct. Obviously the out side diameters and the taper of the plugs may be checked before the threads are put on, in the same manner as is shown in Fig. 5 for a threaded plug. 7

While throughout the description, the edge 2| of the block has been referred to as being vertical, and the edge 23 as horizontal, and the edges l8 and 28 at designated angles with respect to the vertical and horizontal, it will be understood that the device, as shown, may be used with the edge 21 horizontal or at any other angle, and the edge 23 vertical or at any other angle, the requirement being that the edges I8, 20 and 2| be plane surfaces; that the edge surface l8 be at an angle with the surface 2| equal to the apex angle of the taper of the thread being measured; and that the surface I3 be at an angle with the surface 20 equal to plus half the 'apex angle of the taper of the thread.

Inasmuch as the block I9 may have any conplane surfaces 2|, i8 and 28. At the upper end the surface It; leans toward the surface 21 making an angle between surfaces 2! and I8. The

'taper of the plug will be correct if the apex angle of the plug exactly equals the included angle between the plane surfaces 2| and l8. The third and 20 of the block [9 may each have the proper relation to the others, all three surfaces may preferably be described by their relation to a reference plane which passes through the axis of the plug being measured. Such a relation will exist if the reference plane lies in a central longitudinal section through the plug and block as seen in Fig. 6. 7

Having thus described an embodiment of my invention, I claim: e

1. A measuring block for measuring the pitch diameter of a tapered thread plug at the small end of the taper by the three wire system, said measuring block having three plane surfaces related to a refe'renceplane which passes through the axis of said tapered thread plug, the first plane surface being perpendicular to said reference plane, the second'plane surface being perpendicular to said reference plane and so positioned that the line of intersection between said second plane surface and said reference plane makes an angle with the line of intersection of said first plane surface and said reference plane that is equal to the apex angle of the tapered thread plug to be measured, the third plane'surface being perpendicular to said reference plane and so positioned'that the line of intersection between said third plane surface and said reference plane makes an angle with the line of intersection between said second plane surface and said reference plane that is equal to ninety degrees plus one half the apex angle of the tapered thread plug to be measured.

2. A measuring block for measuring the diameter of 'a tapered thread plug at'the small end,

,said measuring block having plane surfaces related to a given reference plane as follows: a first plane surface perpendicular to said reference plane, a second plane surface perpendicular to said reference plane and so positioned that the line of intersection between said second plane. surface and said reference plane makes an angle "with the line of intersection of said first plane, surface and said reference plane that is equal to the apex angle of the tapered thread plug to be measured, a third plane surface perpendicular to said reference plane and so positioned that the line of intersection between.

said third plane surface and said reference plane makes an angle with the line of intersection between said second plane surface and said reference plane that is equal to ninety degrees plus one half the apex angle of the tapered thread plug to be measured, and means positioning said tapered thread plug to be measured adjacent to said second surface and upon said third surface with the axis of said thread plug in said reference plane.

3. A measuring block for measuring the pitch diameter of a tapered thread plug at the small end of the taper by the three wire system, said measuring block having three essential plane surfaces, the first and second plane surfaces converging at an angle equal to the apex angle of said tapered thread plug and the second and third plane surfaces diverging at an angle of ninety degrees plus one half the apex angle of the thread plug, a reference plane passing through the axis of the said plug being normal to all three essential surfaces.

4. A measuring block for measuring the pitch diameter of a tapered thread plug at the small end of the taper by the three-wire system, said measuring block having three essential plane surfaces all normal to a reference plane passing through the plug axis, the first and second plane surfaces converging at an angle which is equal to the apex angle of the plug, the second and third plane surfaces diverging at an angle which is equal to ninety degrees plus half the apex angle of the plug.

5. A device for adapting the three wire thread measuring system for checking the tapers and pitch diameters of pipe threads, which consists of a block having a first plane surface, a second plane surface diverging from the first plane surface at an included angle with the first plane surface equal to the apex angle of the taper of the pipe thread to be measured, and a third plane surface extending laterally from the second plane surface at the most diverged end thereof at an included angle with the second plane surface equal to plus half the apex angle of the pipe thread to be measured, and wherein the distance from the convergence of the said second and the said third surfaces to the said first surface normal to the said first surface is equal to one unit of measurement of the pipe thread to be measured.

HARRY J. GLANZER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Standards for Federal Services, June 15, 1949, Natl. Bureau of Standards. 

